Apparatus for treating materials with chlorine



Patented Dec. 24, 1940 UNITED STATES APPARATUS FOR TREATING MATERIALSwmr crmoama Leslie G. Jenness, Englewood, N. J., assignor to IntermetalCorporation, Newark, N. 1., a corporation of Delaware No Drawing.Application March 7, 1940, Serial No. 322,847

3 Claims.

This invention relates to an apparatus for treating materials withchlorine, and more particularly to such an apparatus in which materialscan be treated .with chlorine at relatively high temperatures.

. Many chemical processes involving the use of chlorine gas atrelatively high temperatures have been suggested. Chlorine is known tobe extremely corrosive for metals under high tem w perature conditionsand prior workers have employed retorts or furnaces of refractorymaterials or have provided metallic structures with refractory liningsso as to prevent contactbe- I tween metals and chlorine at hightemperatures. In accordance with the present invention, I havediscovered that under certain conditions nickel can be made extremelyresistant to corrosion by chlorine at relatively high temo peraturessuch that apparatus, for, example, rea torts or furnaces constructed ofnickel, having nickel linings, or stationary or removable parts made ofnickel, within or associated with the apparatus so as to be contacted bythe chlorine, can be employed for processes involving the use ofchlorine at such relatively high temperatures. More specifically, I havediscovered that the presence of sulfur or a sulfur chloride in suchprocesses involving the use of chlorine will cause a protective film tobe formed upon the surface of the nickel in contact with the reactingmaterials such that the nickel metal is not corroded by chlorine attemperatures as high as 575 C.

An obi ect of the present invention is, therefore, to provide animproved apparatus for treating materials with chlorine in which nickelhaving a protective film is employed.

Another object of the invention is to provide as an article ofmanufacture a metal structure or article consisting essentially ofnickel and having formed thereon a protective film preventing corrosionby chlorine.

As stated above, nickel is known to be rapidly corroded by chlorine.However, by forming the protective film referred to upon the nickel, thenickel may be exposed to chlorine at temperatures up to 575 C. withoutany measurable corrosion. The film forms readily at very lowtemperatures and when once formed will not disap- 50 pear unless thenickel is heated to temperatures above 575 0. The film is black in colorand extremely thin, and shows the qualitative presence of sulfur andchlorine as well as nickel, although it has not thus far been possibleto determine the I exact composition of the film. The formation of thefilm apparently requires the presence of a sulfur chloride but isapparently independent of constituents other than sulfur and chlorine.

It is, of course, apparent that it is not necessa y to introduce asulfur chloride into the reaction 5 chamber in which the film is formed,as the sulfur chloride may be formed in situ. Free sulfur and manysulfur compounds will react with chlorine'to form sulfur chlorides. Thusthe presence of free sulfur or such compounds as iron sulfide 10 orother sulfides, found in many ores, provides for the formation of suchfilm.

The film is extremely thin and resistant to abrasion, as furnacesprovided with nickel rabble arms scraping ores of relatively abrasivenature 15 over nickel surfaces have been employed for extended periodsof time without showing any more than the wear which would be normallyexpected from such operations in the absence of corrosive gases. Whenonce formed, the film is persistent, so as the sulfur or chlorine, orboth, can be removed from contact with nickel and the furnace used forother purposes for considerable lengths of time at temperatures below575 C. without destruction of said film. It is, therefore, entirelypossible to intermittently introduce sulfur, sulfur-containing compoundsor a sulfur chloride into such a furnace to form said film and thusemploy the furnace for continued treatment with chlorine in the absenceof sulfur. The present invention has thus far found its chief utility inthe chlorination of ores to remove volatile compounds of metal, chlorineand sulfur, as disclosed in Patents Nos. 1,834,622; 1,923,094; 1,858,272and 1,863,599. A structure of a furnace suitable for carrying out theprocesses of the above patents is disclosed in my Patent No. 2,116,725.Such a furnace includes many moving parts and also the provision atexternal heating means for supplying heat through the walls of thetreating chamber to the materials being treated in order to maintain thenecessary or desirable treating temperature. It was, therefore,desirable to construct such a furnace of metahbut no suitable metal wasknown prior to the present invention which could be commercially used.The film has been formed and maintained in furnace work with titanium,vanadium, tungsten and aluminum bearing ores, indicating that theformation of film is independent of constituents other than thechlorinating gases containing chlorine and a sulfur chloride. It isevident that the present invention is not limited to the treatment ofores but may be employed in any process involving the which the presenceof sulfur is not objectionable.

It has also been found that the film will be I formed upon nickelalloys, the major portion of which consists of nickel. Thus nickelalloys can be employed under certain conditions, although the presenceof substantial amounts of other metals in the alloy somewhat reduces thetemperature of operation. Fbr example, a 90% nickel-10% chromium alloyhas been found satisfactory up to a temperature of 525 to 550 C., thefilm disappearing at only a slightly lower temperature than with purenickel. It will be seen that I have provided an apparatus by whichmaterials can be treated with chlorine at relatively high temperaturesin metallic reaction chambers without corrosion, thus providing fortreating chambers having high mechanical strength and the efllcientapplication of external heat to the reaction.

It is apparent that articles of manufacture, for example, pipes, valves,machine parts, or sheets of nickel or metals containing a major portionof nickel may have one or more surfaces provided with the protectivefilm of the present invention and may be sold or used for purposes inwhich the metal is subjected to corrosion by chlorine. After once beingformed, the film is resistant to abrasion and persistent in the presenceof chlorine as well as in the presence of chlorine and sulfur chloride.Furthermore, the film has been found to withstand weathering forextended periods of time upon articles exposed in the open. The film maybe formed upon such articles by treating them in: a chamber containingchlorine and sulfur chloride or. in the ,case of hollow articles such aspipes or reaction chambers, by circulating chlorine and sulfur chloridetherethroughorintroduclngthesame thereinto. Also, a layer of nickel or anickel alloy consisting essentially of nickel may be plated or otherwiseformed upon a base metal and the film formed upon the surface of thelayer.

This application is a continuation in part of my co-pending applicationserial No. 198,158, flied March 25, 1938.

While I have disclosed the preferred embodiments of my invention, it isto be understood that the details thereof may be varied within the scopeof the following claims.

I claim: 1

1. As an article of manufacture, a structure having a surface of metalcontaining a malor portionof nickel, said surface being provided with anintegral protective film consisting of said metal of said surface,chlorine, and sulfur.

2. As an article of manufacture, a nickel metal structure having anickel surface provided with an integral protective film consisting ofsaid nickel, chlorine, and sulfur.

3. As an article of manufacture, a metal structure having a surfacelayer of metal containing a major portion of nickel, said layer havingits exposed surface provided with an integral protective film consistingof said metal of said layer, chlorine, and sulfur.

LESLIE G. JENNESS.

